Moving ship tomography a first look at BASSEX 04

During the Basin Acoustic Seamount Scattering Experiment (BASSEX04) a line array was towed between two source moorings in the North Pacific separated by 500 km. The moorings were part of the SPICE04 test led by Scripps Institution of Oceanography. Each mooring had two broadband sources (center frequency 250 Hz) at depths of nominally 800 m and 3000 m. Thirty transmissions were recorded as the ship passed south along the line bisecting the two source moorings. The sources transmitted simultaneously (for each source). In order to break the conical ambiguity of the arrivals from each source, the array was turned 20 degrees for each reception. One set of sources used coded m-sequences with different laws, permitting separation of the signals by signal processing. Comparisons of the received signals will be compared with initial propagation model results using the measured sound speed field from the ship. An approach to Nx2−D tomography (where N=30) will be investigated. [Work supported by ONR Ocean Acoustics.]